2 x240-pin DIMM, Max. 8 GB, DDR3 1333(O.C.)/1066/800 Non-ECC,Un-buffered MemoryDual Channel memory architecture** Refer to www.asus.com or user manual for Memory QVL (Qualify Vendor List)*** When installing total memory of 4GB capacity or more, Windows® 32-bit operation system may only recognize less than 3GB. Hence, a total installed memory of less than 3GB is recommended.